** Symbolic factorization analysis. **

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** count = SYMBFACT(A) returns the vector of row counts for the upper **

** triangular Cholesky factor of a symmetric matrix whose upper triangle **

** is that of A, assuming no cancellation during the factorization. **

** This routine should be much faster than chol(A). **

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** **

** count = SYMBFACT(A,'col') analyzes A'*A (without forming it explicitly). **

** count = SYMBFACT(A,'sym') is the same as p = symbfact(A). **

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** There are several optional return values: **

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** [count,h,parent,post,R] = symbfact(...) also returns **

** the height of the elimination tree, **

** the elimination tree itself, **

** a postordering permutation of the elimination tree, **

** and a 0-1 matrix R whose structure is that of chol(A). **

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** See also CHOL , ETREE , TREELAYOUT . **

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